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/*
* Copyright 2006 Andi Kleen, SUSE Labs.
* Subject to the GNU Public License, v.2
*
* Fast user context implementation of clock_gettime, gettimeofday, and time.
*
* The code should have no internal unresolved relocations.
* Check with readelf after changing.
* Also alternative() doesn't work.
*/
/*
* Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
*/
/* Disable profiling for userspace code: */
#ifndef DISABLE_BRANCH_PROFILING
#define DISABLE_BRANCH_PROFILING
#endif
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/string.h>
#include <asm/io.h>
#include <asm/unistd.h>
#include <asm/timex.h>
#include <asm/clocksource.h>
#include <asm/vvar.h>
#undef TICK_PRIV_BIT
#ifdef CONFIG_SPARC64
#define TICK_PRIV_BIT (1UL << 63)
#else
#define TICK_PRIV_BIT (1ULL << 63)
#endif
#define SYSCALL_STRING \
"ta 0x6d;" \
"sub %%g0, %%o0, %%o0;" \
#define SYSCALL_CLOBBERS \
"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15", \
"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23", \
"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31", \
"f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46", \
"f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62", \
"cc", "memory"
/*
* Compute the vvar page's address in the process address space, and return it
* as a pointer to the vvar_data.
*/
static notrace noinline struct vvar_data *
get_vvar_data(void)
{
unsigned long ret;
/*
* vdso data page is the first vDSO page so grab the return address
* and move up a page to get to the data page.
*/
ret = (unsigned long)__builtin_return_address(0);
ret &= ~(8192 - 1);
ret -= 8192;
return (struct vvar_data *) ret;
}
static notrace long
vdso_fallback_gettime(long clock, struct timespec *ts)
{
register long num __asm__("g1") = __NR_clock_gettime;
register long o0 __asm__("o0") = clock;
register long o1 __asm__("o1") = (long) ts;
__asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
"0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
return o0;
}
static notrace __always_inline long
vdso_fallback_gettimeofday(struct timeval *tv, struct timezone *tz)
{
register long num __asm__("g1") = __NR_gettimeofday;
register long o0 __asm__("o0") = (long) tv;
register long o1 __asm__("o1") = (long) tz;
__asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
"0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
return o0;
}
#ifdef CONFIG_SPARC64
static notrace noinline u64
vread_tick(void) {
u64 ret;
__asm__ __volatile__("rd %%asr24, %0 \n"
".section .vread_tick_patch, \"ax\" \n"
"rd %%tick, %0 \n"
".previous \n"
: "=&r" (ret));
return ret & ~TICK_PRIV_BIT;
}
#else
static notrace noinline u64
vread_tick(void)
{
unsigned int lo, hi;
__asm__ __volatile__("rd %%asr24, %%g1\n\t"
"srlx %%g1, 32, %1\n\t"
"srl %%g1, 0, %0\n"
".section .vread_tick_patch, \"ax\" \n"
"rd %%tick, %%g1\n"
".previous \n"
: "=&r" (lo), "=&r" (hi)
:
: "g1");
return lo | ((u64)hi << 32);
}
#endif
static notrace inline u64
vgetsns(struct vvar_data *vvar)
{
u64 v;
u64 cycles;
cycles = vread_tick();
v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
return v * vvar->clock.mult;
}
static notrace noinline int
do_realtime(struct vvar_data *vvar, struct timespec *ts)
{
unsigned long seq;
u64 ns;
ts->tv_nsec = 0;
do {
seq = vvar_read_begin(vvar);
ts->tv_sec = vvar->wall_time_sec;
ns = vvar->wall_time_snsec;
ns += vgetsns(vvar);
ns >>= vvar->clock.shift;
} while (unlikely(vvar_read_retry(vvar, seq)));
timespec_add_ns(ts, ns);
return 0;
}
static notrace noinline int
do_monotonic(struct vvar_data *vvar, struct timespec *ts)
{
unsigned long seq;
u64 ns;
ts->tv_nsec = 0;
do {
seq = vvar_read_begin(vvar);
ts->tv_sec = vvar->monotonic_time_sec;
ns = vvar->monotonic_time_snsec;
ns += vgetsns(vvar);
ns >>= vvar->clock.shift;
} while (unlikely(vvar_read_retry(vvar, seq)));
timespec_add_ns(ts, ns);
return 0;
}
static notrace noinline int
do_realtime_coarse(struct vvar_data *vvar, struct timespec *ts)
{
unsigned long seq;
do {
seq = vvar_read_begin(vvar);
ts->tv_sec = vvar->wall_time_coarse_sec;
ts->tv_nsec = vvar->wall_time_coarse_nsec;
} while (unlikely(vvar_read_retry(vvar, seq)));
return 0;
}
static notrace noinline int
do_monotonic_coarse(struct vvar_data *vvar, struct timespec *ts)
{
unsigned long seq;
do {
seq = vvar_read_begin(vvar);
ts->tv_sec = vvar->monotonic_time_coarse_sec;
ts->tv_nsec = vvar->monotonic_time_coarse_nsec;
} while (unlikely(vvar_read_retry(vvar, seq)));
return 0;
}
notrace int
__vdso_clock_gettime(clockid_t clock, struct timespec *ts)
{
struct vvar_data *vvd = get_vvar_data();
switch (clock) {
case CLOCK_REALTIME:
if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
break;
return do_realtime(vvd, ts);
case CLOCK_MONOTONIC:
if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
break;
return do_monotonic(vvd, ts);
case CLOCK_REALTIME_COARSE:
return do_realtime_coarse(vvd, ts);
case CLOCK_MONOTONIC_COARSE:
return do_monotonic_coarse(vvd, ts);
}
/*
* Unknown clock ID ? Fall back to the syscall.
*/
return vdso_fallback_gettime(clock, ts);
}
int
clock_gettime(clockid_t, struct timespec *)
__attribute__((weak, alias("__vdso_clock_gettime")));
notrace int
__vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
struct vvar_data *vvd = get_vvar_data();
if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
if (likely(tv != NULL)) {
union tstv_t {
struct timespec ts;
struct timeval tv;
} *tstv = (union tstv_t *) tv;
do_realtime(vvd, &tstv->ts);
/*
* Assign before dividing to ensure that the division is
* done in the type of tv_usec, not tv_nsec.
*
* There cannot be > 1 billion usec in a second:
* do_realtime() has already distributed such overflow
* into tv_sec. So we can assign it to an int safely.
*/
tstv->tv.tv_usec = tstv->ts.tv_nsec;
tstv->tv.tv_usec /= 1000;
}
if (unlikely(tz != NULL)) {
/* Avoid memcpy. Some old compilers fail to inline it */
tz->tz_minuteswest = vvd->tz_minuteswest;
tz->tz_dsttime = vvd->tz_dsttime;
}
return 0;
}
return vdso_fallback_gettimeofday(tv, tz);
}
int
gettimeofday(struct timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
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